Burner for light combustible materials

ABSTRACT

A method and two embodiments of apparatus for providing efficient combustion wherein air and combustible materials are introduced into a bottom portion of a vertical chamber which is substantially open at its top, the combustible material being dispersed upwardly through a combustion zone with combustion products exiting through the open top of the chamber, gases which tend to be trapped beneath the combustion zone being vented from the chamber through suitable conduits and returned to an upper portion of the chamber if desired for more complete combustion. One embodiment of the apparatus includes a feed duct extending downwardly through the chamber for introducing combustible material thereinto. Another embodiment of the apparatus includes a feed assembly with a hopper and feed mechanism for respectively receiving combustible material and urging it upwardly through a feed duct into the chamber.

Gardner [11] 3,818,848 [451 June 25, 1974 BURNER FOR LIGHT COMBUSTIBLE MATERIALS [76] Inventor: Orian R. Gardner, 419 Marin Ave.,

Mill Valley, Calif. 94941 [22] Filed: Mayl6, 1973 [21] Appl. No.: 360,927

Related US. Application Data [62] Division of Ser. No. 163,869, July 19, 1971, Pat. No.

Primary Examinerl(enneth W. Sprague Attorney, Agent, or Firm-Phillips, Moore, Weissenberger, Lempio & Strabala [57] ABSTRACT A method and two embodiments of apparatus for providing efficient combustion wherein air and combustible materials are introduced into a bottom portion of a vertical chamber which is substantially open at its top, the combustible material being dispersed upwardly through a combustion zone with combustion products exiting through the open top of the chamber, gases which tend to be trapped beneath the combustion zone being vented from the chamber through suitable conduits and returned to an upper portion of the chamber if desired for more complete combustion. One embodiment of the apparatus includes a feed duct extending downwardly through the chamber for introducing combustible material thereinto. Another embodiment of the apparatus includes a feed assembly with a hopper and feed mechanism for respectively receiving combustible material and urging it upwardly through a feed duct into the chamber.

4 Claims, 2 Drawing Figures PATENTEB JUN2S m4 FIG 2 l l BURNER FOR LIGHT COMBUSTIBLE MATERIALS This is a division of Ser. No. 163,869, filed July 19, 1971, now US. Pat. No. 3,744,440.

RELATED U .S. PATENTS US. Pat. Application Ser. No. 821,897, entitled Rice Hull Burners and filed on May 5, 1969 by Orian R. Gardner, now US. Pat. No. 3,626,876, issued on Dec. 14,1971.

The present invention relates to combustion apparatus and methods particularly adapted for the burning of light combustible materials such as rice bulls and straw from various grains for example. Various devices and methods are known in the prior art for these'purposes. However, there remains a need for improvements to meet various requirements for combustion apparatus and processes. One such general requirement is the provision of efficient and economical means for burning such materials. There are often substantial quantities of such materials which can be processed or disposed of only by burning. ln'many cases, combustion products from these materials does not provide an economic return. Accordingly, it is desirable that capital and operating costs for the combustion process be minimal.

1n the processing of other materials such as rice hulls for example, the ash or combustion product may be usable and thus permit an economic return. However, the need for efficiency and economy remains. In addition for combustible materials of this type, it is necessary to provide for accurate control or regulation'ofthe combustion process in order to provide various desired properties in the combustion products.

An additional requirement is raised by the pollution controls enacted in many states. This consideration has become substantially important. Relatively precise limits have commonly been enacted particularly for the burning of large quantities of materials and these limits may be made even more restrictive in the future. Generally, these pollution controls require quite close control over the combustion apparatus or method. Particular combustion features offered by the present invention for meeting these controls include the manner of introducing combustible materials into a combustion region and the degree or rate of combustion which may be uniformly maintained to regulate both the quality a and quantity of combustion products, either solids or gases, which are introduced into the atmosphere.

The reference cited above provides a burner which overcomes many of the problems and tends to meet the various requirements set forth above. The burner described in that reference is of relatively simple construction including a vertical chamber with combustibles and air being introduced in a bottom portion of the chamber and pass upwardly through a combustion region while combustion products pass out of the chamber through an opening at the top. Such a design has been found to permit good control over the combustion process.

However, under certain conditions such as when combustible material having a high moisture content is being burned for example, the combustion process may tend to be disrupted by steam becoming trapped beneath solid material suspended in the chamber during combustion. When pressure of the steam is sufficiently high, it erupts upwardly through the suspended solids and tends to interfere with the otherwise uniform combustion characteristics.

Accordingly, one object of the present invention is to provide a combustion apparatus and method which is capable of overcoming or avoiding such problems. For this purpose, vent means are placed in a vertical combustion chamber below a substantial portion of a combustion zone wherein combustible solids tend to be suspended for relieving trapped gases such as steam. The vented gases may be reintroduced into the chamber if desired for more complete burning of any combustible materials therein.

Lighters may also be used in conjunction with the chamber to introduce combustion supporting fluids or material such as fuel, for example, to maintain high temperatures in the combustion zone and to establish or maintain desired combustion characteristics.

It is also an object of the present invention to provide a burner of the general type described above being particularly adapted to the burning of relatively light combustible materials such as straw which may be somewhat difficult to handle because of its bulkiness. In one embodiment of the invention for example, a feeder assembly includes hopper means for receiving combustible material'and a feed mechanism for urging the material through a feed duct into the chamber. With the feed duct penetrating the bottom of the chamber, the entire chamber interior is also available to form the combustion zone. This feature is of particular advantage for bulky materials since material may be burned at a greater rate. The gas vent and/or lighter arrangements may also be used to advantage in this embodimentfor example when straw or other material having a relatively high moisture content is being burned.

Other advantages and objects of the present invention are believed apparent in the followwng description of method and'apparatus embodiments of the present invention which are also illustrated in the accompanying drawings.

BRIEF DESCRIPTION or THE DRAWINGS FIG. 1 is a side view in elevation of a burner constructed' according to the present. invention and suitable for practicing the method of the present invention; and

FIG. 2 is a similar view of another embodiment of a burner construced according to the present invention.

A preferred embodiment of the present invention as illustrated in FIG. 1 may be adapted for the combustion of various materials, particularly relatively light com bustible materials such as rice hulls and straw for example, which can be suspended or carried upwardly through a combustion zone by air and/or convection currents.

Referring now to FIG. 1, a housing 11 forms a gener ally vertical combustion chamber 12 which is open at its top. A concentrically arranged feed duct 13 opens into a bottom portion of the chamber and is supported by tie-rods 14. The bottom portion 15 of the feed duct tapers inwardly toward an opening 16. The top portion 17 of the cylindrical feed duct flares outwardly to form a hopper for receiving combustible material which pass downwardly through the duct into the chamber 12. The feed duct of this embodiment is particularly adapted for use with relatively free-flowing combustible materials. However, additional means may be employed for 3, urging combustibles through the duct if necessary in a manner somewhat like that described below with reference to the embodiment of FIG. 2, for example. The size of the feed duct with respect to the housing 11 may be selected to optimize the feed rate with respect to the rate of combustion in the chamber for various materials.

Air for supporting combustion in the chamber is introduced at the base of the chamber through inlet ports 18. Air flow through the ports 18 may be induced by convection currents in the chamber once combustion commences or it may be forced therethrough by a conventional manifold and blower of the type described and illustrated in the reference noted above, for example.

Agitator means 19 are arranged in the bottom of the chamber 12 for dispersing combustible material passing downwardly out of the feed duct 13. The agitator also assists in intermixing the combustibles with air from the ports 18 and urging it upwardly in the chamber toward a combustion zone discussed in greater detail below. The agitator means as illustrated in FIG. 1, is a bladed element secured to a shaft 21 which rotatably penetrates the floor 22 of the chamber 12 and is driven by a motor 23 through suitable reduction gearing 24. The reduction gearing may include conventional variable means (not shown) for adjusting the speed of rotation for the agitator.

For handling combustible materials which tend to be cohesive, such as straw for example, breaker means 26 are arranged between the agitator and the opening 16 of the feed duct. The breaker means as illustrated in FIG. 1, comprises a curved rod which is also mounted on the shaft 21 for rotation with the agitator 19. This rod structure serves to initially scatter combustible material exiting the feed duct so that it may be more readily dispersed by the agitator.

When the combustion apparatus of the present invention is employed for burning certain materials such as combustibles having a relatively high moisture content, additional means are contemplated for providing uniform and controllable combustion conditions in the chamber. Prior to describingthese means it is noted that in operation of the present device, combustibles are dispersed by the agitator and carried upwardly through the chamber 12 either by air flow or by convection currents after the material is ignited and combustion is commenced. During combustion, the material tends to be suspended in a combustion zone, generally indicated at 27, which is formed along the vertical chamber 12. After combustion of succeeding portions of the materialis complete, the degree of combustion depending on the particularly type of material being burned, its feed rate, temperature in the chamber and the rate of air flow which are selected for example, solid and gaseous combustion products are carried upwardly and out of the open top of the chamber around the feed duct portion I7.

Since substantial quantities of materials may be suspended in the chamber during combustion and since the combustible material is fed upwardly into the combustion chamber, gases such as steam may become trapped below or in a lower portion of the combustion zone 27. When pressure of the trapped gas rises sufficiently, it tends to erupt upwardly through the suspended combustible material. When this occurs, the uniform rate of combustion proceeding in the zone 27 is disrupted. Part of the combustible materials in the zone 27 may also be carried upwardly and out of the chamber 12 by the erupting gas before it has been oxidized to the degree desired.

To overcome this problem, vent means such as orifices 28 illustrated in the embodiment of FIG. 1 are arranged below a substantial portion of the combustion zone 27 for releasing the trapped gases from the chamber and permitting uniform and controllable combustion.

As illustrated in FIG. 1, the orifices 28 are formed by the bottom openings of a plurality of tubes 29 which are circumferentially arranged about the chamber 12 and which may be simply secured to the housing 1 1 for example.

The arrangement of tubes 29 also facilitates better pollution control for the device since the upper ends 31 of the tubes open into the chamber at least above a substantial portion of the combustion zone 27. Thus, the vented gases are reintroduced into the chamber to permit more complete oxidation of any combustible material remaining therein. As will be more apparent from the following description with reference to the embodiment of FIG. 2, the orifices 28 may also be simply formed in the housing itself so that the gases are merely vented to the atmosphere, for example, when no combustibles are present in the gas.

Certain operating conditions, such as during the burning of materials with high moisture contents, may tend to undesirably reduce the temperature in the combustion zone. To overcome this problem, lighter means such as the tubes 32 are contemplated around the chamber for introducing combustion supporting material or fluid, such as various petroleum products or even additional air for example, into the chamber adjacent the combustion zone 27. Such material may be delivered into the tubes 32 for introduction into the chamber from a suitable source or air may be simply allowed to flow into the chamber under the influence of convection currents in the chamber. Regardless of the material to be introduced into the chamber through the tubes, some control means such as a control valve (not shown) may be desired to either close the tubes or regulate the flow of material therethrough to further vary combustion properties in the chamber.

Another embodiment of the invention, having reference now to FIG. 2, includes a combustion device which is generally similar to that of FIG. 1. Accordingly, features of the embodiment in FIG. 2 are indicated by similar primed numerals.

The chamber 12 of FIG. 2 is generally similar to the chamber 12 of FIG. 1. However, the feed duct 13, while delivering material into the base of the chamber like the duct 13 of FIG. 1, is arranged outside the chamber and penetrates its floor 22. Thus, the entire chamber interior is open and available to form the combustion zone therealong. The extent of the zone along either of the vertical chambers 12 or 12 of course depends on the type of material being burned and other parameters as discussed above.

This open feature of the chamber 12 makes it particularly useful for burning material such as straw for example, the effective volume of which is rapidly reduced during combustion. The material may be introduced at a faster rate into the entirely open chamber.

Similar vent means are employed as in the embodiment of FIG. 1. However, the tubes 29 are externally arranged about the housing with their lower and upper openings 28 and 31' being formedin the housing or wall 11.

In the embodiment of FIG. 2, the feed duct 13' is part of a feeder assembly 51.. The feeder assembly includes a hopper 52 having a downspout or throat 53 intersecting the feed duct l3'. A feed mechanism 54 includes reciprocable elements 56 and 57 pivotally coupled for operation by a single flywheel 58 which may be driven for example by a motor (not shown). Combustible material placed in the hopper is urged or packed into the feed duct 13' by the element 56 while the element 57 urges material through the duct 13'. into the chamber.

Such an arrangement is particularly suited for materials such as straw which are difficult to handle and which may be desirable if somewhat-compressed before 13', air is also introduced through the means 18 or 18'.

During combustion, the material is dispersed by the agitator 19 or 19' and carried upwardly into the combustion zone by airflow or convection currents with the material tending to remain suspended in the combustion zone until combustion is complete to a desired degree. Combustion products, both solid and gaseous, pass upwardly from the combustion zone and out the open top of the chamber.

The vent means and lighter means may be selectively employed, either alternatively or in combination, to further enhance desired combustion characteristics in the chamber. As discussed above, gases trapped below the combustion zone may be vented out of the chamber and reintroduced into the chamber above the combustion zone if desired or necessary. The lighter means may be employed as desired to maintain combustion in the zone 27 or 27 Materal exiting the chamber may be further treated or cured, particularly if a usable product is to be obtained for example from the burning of rice hulls. The curing may comprise storing the combustion product in a substantial mass so that it is further affected by residual heat as discussed in the reference noted above. It may also comprise rapid cooling of the combustion product for example by immersion in water to prevent further thermal oxidation or reduction thereof.

Although various preferred embodiments have been described above, it is believed that numerous variations and modifications are possible within the spirit and scope of the invention. Particularly, it is apparent that numerous elements such as the venting arrangements of FIGS. 1 and 2 may be interchanged for various applications. Accordingly, the scope of the present invention is defined by the following claims.

I claim: 1. Apparatus for burning'light combustible materials, comprising a vertically arranged combustion chamber having an opening at its top, means for delivering combustible material and air into a bottom portion of the chamber, combustion of the material occurring as it moves upwardly through a combustion zone formed generally midway along the vertical chamber with combustion products exiting the chamber through its open top, vent means in communication with the chamber interior below a substantial portion of the combustion zone for releasing gases tending to be trapped in the chamber by combustible material in the combustion zone, and a feeder assembly in communication with the chamber base by means of a feed duct, the feeder assembly comprising hopper means for receiving combustible material and feed means for urging the combustible material through the feed duct into the chamber base. 2. The apparatus of claim 1 further comprising manifold means in communication withthe chamber adjacent its base by means of openings formed in a wall portion of the chamber and rotatable breaker means arranged in the chamber base adjacent the feed duct for scattering combustible material and facilitating its upward dispersement through the chamber together with air from the manifold means.

3. The apparatus of claim 2 further comprising lighter means in communication with the chamber interior generally adjacent the combustion zone for introducing combustion supporting material thereinto.

4. Combustion apparatus comprising a vertically arranged combustion chamber having an opening at its top, a feeder assembly in communication with the bottom of the chamber interior by means of an external feed duct, the feeder assembly comprising hopper means for receiving combustible material and feed means for urging the combustible material through the feed duct into the chamber base and means for introducing air into the base of the chamber and agitating,

the combustible material so that it intermixes with the air and is dispersed upwardly through the chamber with combustion occurring in a combustion zone formed along the vertical chamber, solid and gaseous combustion products which are formed in the combustion zone exiting through the opening at the top of the chamber. *1 

1. Apparatus for burning light combustible materials, comprising a vertically arranged combustion chamber having an opening at its top, means for delivering combustible material and air into a bottom portion of the chamber, combustion of the material occurring as it moves upwardly through a combustion zone formed generally midway along the vertical chamber with combustion products exiting the chamber through its open top, vent means in communication with the chamber interior below a substantial portion of the combustion zone for releasing gases tending to be trapped in the chamber by combustible material in the combustion zone, and a feeder assembly in communication with the chamber base by means of a feed duct, the feeder assembly comprising hopper means for receiving combustible material and feed means for urging the combustible material through the feed duct into the chamber base.
 2. The apparatus of claim 1 further comprising manifold means in communication with the chamber adjacent its base by means of openings formed in a wall portion of the chamber and rotatable breaker means arranged in the chamber base adjacent the feed duct for scattering combustible material and facilitating its upward dispersement through the chamber together with air from the manifold means.
 3. The apparatus of claim 2 further comprising lighter means in communication with the chamber interior generally adjacent the combustion zone for introducing combustion supporting material thereinto.
 4. Combustion apparatus comprising a vertically arranged combustion chamber having an opening at its top, a feeder assembly in communication with the bottom of the chamber interior by means of an external feed duct, the feeder assembly comprising hopper means for receiving combustible material and feed means for urging the combustible material through the feed duct into the chamber base and means for introducing air into the base of the chamber and agitating the combustible material so that it intermixes with the air and is dispersed upwardly through the chamber with combustion occurring in a combustion zone formed along the vertical chamber, solid and gaseous combustion products which are formed in the combustion zone exiting through the opening at the top of the chamber. 